[Determination of surface energy of PS-PEO-PS triblock copolymers by inverse gas chromatography].

The surface energy(gamma sd) of the dispersive component of the triblock copolymers, poly(styrene)-poly (ethylene oxide)-poly(styrene)(PS-PEO-PS), was determined by using inverse gas chromatography(IGC). A series of linear alkanes were used to determine the free energy of adsorption (delta GCH2) of a CH2 group in a temperature range of 70 degrees C-120 degrees C, and gamma sd of PS-PEO-PS were calculated. The effects of the polymer composition and temperature on gamma sd values were discussed. IGC data indicated that gamma sd values of PS-PEO-PS were lower (gamma dPS-PEO-PS-1 = 16.99 mJ.m-2, gamma dPS-PEO-PS-2 = 17.98 mJ.m-2, 70 degrees C) than that of PEG (gamma dPEG = 21.74 mJ.m-2, 70 degrees C), and increased as the ethylene oxide content increased in PS-PEO-PS. The gamma sd was sensitive to temperature, decreased sharply with the increase of temperature. Linear relationships were obtained between the gamma sd and temperature (t, degree C), which were gamma dPE-PEO-PS-1 = 28.12-0.161t and gamma dPS-PEO-PS-2 = 28.23-0.148t.

[Study of the crystalline behaviors of polymer by inverse gas chromatography].

An investigation was made on crystallinity(Xc) and melting temperature(Tm) of the crystalline polymer polyethylene glycol(PEG) by inverse gas chromatography(IGC). The influence of the property of the probe and the coating weight of PEG in stationary phase on the data determined is discussed. And IGC data are compared with those got by differential scanning calorimetric (DSC) experiment. Results showed that IGC is a very useful technique for measuring the melting point and the degree of crystallinity of polymer samples since it does not depend on the assumptions about the properties of 100% crystalline polymer. IGC data indicated that the melting temperature of PEG was 67 degrees C and crystallinity was 89.7%. DSC data indicated the same results. The experimental data was found to be not related with the chemical nature of the probes, but depended on the coating weight of PEG on the supports.

[Separation model of small molecules with SEC columns and micellar mobile phase].

Small alkanol molecules were successfully separated with SEC method in combination with a micellar mobile phase. The separation model has been given in this system. The separation is based on the differential migration of the micelle and the surrounding water and the differential distribution of the solute between the micelle and aqueous phase, therefore, the separation mechanism is very similar to that of micella electrokinetic chromatography (MEKC). The retention volume of solute is related to the micellar concentration by theoretical treatment, through which the solute distribution coefficient between micelle and aqueous phase could be obtained. Two different SEC columns were employed for separation of some alkanols and the theoretical model is supported by the experimental results. The distribution coefficients obtained were in good agreement for these two columns.

Digital replantation in children: a long-term follow-up study.

Twenty-six children aged from 14 months to 12 years had a total of 44 amputated digits replanted in our hospital between May 1979 and May 1985. The length of follow-up was from 9 to 15 years (average, 11 years). Among the 43 surviving digits, the mean total active motion of the thumb and fingers was 130 degrees and 151 degrees, respectively. Sensibility recovery was excellent, with normal 2-point discrimination in 88%. A mean of 19 of 20 preselected activities of daily living could be accomplished. Relative grip strength was 79% that of the normal side and the relative pinch strength was 88%. Cold intolerance was slight or moderate in 40% of patients, and slight atrophy was present in 12 digits. Angulatory deformity or malalignment were remodeled. The circulatory status of the replanted fingers was excellent in 88% of digits and good in 12%. Bone growth had a mean relative length of 93% of normal in digits without joint involvement and 88% in those with joint involvement. Assessed with Nakamura Tamai criteria, the results were excellent in 25 cases (96%) and good in 1. All patients and their parents were satisfied with the results of the digital replantation.

[Thumb and finger reconstruction by anastomosing the digital arteries of the toe to finger transplant].

In a series of 295 cases of toe-to-finger reconstruction, 30 cases with 40 digits were reconstructed by arterial anastomosis between digital arteries of the toe transplant and the recipient thumb or fingertoe. Among them 5 thumbs were reconstructed by the distal segment of the big toe. 11 thumbs (10 cases), 15 fingers (8 cases) and 1 case with concomitant thumb and 3 fingers were reconstructed by toe transfer. Six cases of thumb pulp defect were also reconstructed by the big toe pulp transfer. The anastomosis of digital arteries instead of dorsalis pedis artery and radial artery and saphenous vein with cephali vein to re-establish circulation is an innovation and has the advantages of simplifying the operative procedure, minimizing operative trauma, reducing operation time, attenuating patients suffering, and obtaining good appearance and function after reconstruction. Besides the operation would not be hindered by anatomical variations of the artery and would reduce blood supply disturbance of the donor foot.

Digital replantation. A ten-year retrospective study.

Eight hundred and two digits (592 complete amputation and 210 incomplete amputations) of 549 patients were replanted. The male to female ratio was 3:1 and the age range 1-63 years. 728 digits survived and 74 digits failed. The overall survival rate was 90.8%. Special varieties of complicated amputation were encountered in this series: (1) distal segment replantation, 139 digits, 131 digits (94%) survived; (2) digital replantation of children, 45 cases, 78 digits, average age 3.8 years, the youngest being 1 year old, 68 digits survived (88.7%); (3) rotational avulsion amputation of thumb, 26 digits, 23 digits (88.4%) survived; (4) bilateral digit amputation, 8 cases, 44 digits amputated, 38 digits replanted, including 9 digits of a ten-digit guillotined case. All the digits were salvaged. We conclude that thorough debridement, meticulous anastomosis of blood vessels and timely management of vascular crisis are keys to high survival rate, while judicious selection of indication, proper internal fixation of bone, anastomosis of as many blood vessels as possible, attentive repair of nerves and tendons, sound rehabilitation program are important measures in improving postoperative function.

Digital replantation in children.

This article reports a series of 21 cases of digital replantation in children between 14 months and 10 years of age (mean age, 3 1/2 years) who had a total of 32 digits traumatically amputated. The amputation levels were proximal phalanx in 15 digits, proximal interphalangeal joint in 3 digits, middle phalanx in 3 digits, and distal interphalangeal joint in 11 digits. All but one digit survived after replantation, for an overall survival rate of 96.6%. The longest ischemic time was 28 hours. Several technical points related to the success of this series of cases are discussed in detail.